Trigger latencies + monitoring (v5)

[MRiganSUSX]

This PR implements monitoring of latencies across trigger. Requires appmodel PR: https://github.com/DUNE-DAQ/appmodel/pull/126.

Changes:

• new latency class that is used throughout: simple, stores and retrieves timestamps. Can be configured to use ms or us.
• currently implemented in: CTCM, RTCM, MLT, TXProcessors, HSISM
• also publishes latency information to opmon (all above), using shared proto message for easy changes. Grafana plots are already in place.
• 'weird' case for MLT where two instances are used, one is for readout windows (as was the case in v4)

For appmodel changes:

• created LatencyMonitoringCong class, simply allowing to enable/disable latency monitoring
• instantiated object using this class
• expanded relevant classes and objects that are using this. Tried to abstract the configuration to limit copies of the same code (ie made part of DataProcessor), but not sure it's the best it could have been.

other small changes:

• removed tlog block in DHM (left in by mistake)
• some consistency changes for opmon variables

[MRiganSUSX]

Thanks @ArturSztuc and @mroda88 for insights.

Here is v2, changes: In trigger:

• reworked the latency class (again), to be simpler, and modular
• optimized the if conditions check as Artur suggested
• moved config loading to init or conf as requested
• the default for latency instances is now us (microseconds) throughout (and plots have been updated to reflect this, thanks to @mroda88)

In appmodel:

• previous PR was closed (https://github.com/DUNE-DAQ/appmodel/pull/126)
• new PR: https://github.com/DUNE-DAQ/appmodel/pull/141
• this is using attributes only to pass on the latency boolean

This was tested:

• offline with example configs with additional debug logs
• using the ehn1 example sessions and monitoring plots at grafana
• using dbt-unittest-summary.sh
• using integration tests: minimal_system_quick_test, tpstream_writing_test, 3ru_1df_multirun_test

Some issues and potential improvements are mentioned https://github.com/DUNE-DAQ/trigger/issues/347, for future consideration.

[MRiganSUSX]

Thanks Artur, I updated the standalone makers to only report latency out now. This unfortunately needed a different opmon message, so that we are not sending a message that is half empty.